Wind-induced responses and dynamics characteristics of an asymmetrical base-isolated building observed during typhoons (original) (raw)

Field measurements of typhoon effects on a super tall building

Engineering Structures, 2004

Di Wang Tower located in Shenzhen has a height of approximately 325 m and was the tallest building in Mainland China when it was built several years ago. The aspect ratio between the building's height and transverse width is about 9, which has largely exceeded the criteria in the current design codes and standards in China. This super tall building may be susceptible to severe vibration induced by strong winds. This paper describes some results obtained from the full-scale measurements of wind effects on Di Wang Tower under typhoon condition. The field data, such as wind speed, wind direction and acceleration responses were simultaneously and continuously measured from this building during the passage of Typhoon Sally in 1996. Detailed analysis of the field data was conducted to investigate the typhoon effects on the super tall building. The characteristics of the typhoon-generated wind and the structural responses of the building are presented and discussed in detail. Dynamic characteristics of the building are reported, and comparisons with those from the analysis of the three-dimensional finite element model of Di Wang Tower are made. The serviceability of this super tall building under typhoon conditions is assessed based on the field measurements. The damping ratios of the building during the typhoon are evaluated, and the amplitude-dependent characteristics of damping that were obtained using the random decrement technique are presented on the basis of the field measurements. Furthermore, the full-scale measurements are compared with the wind tunnel test results to verify the reliability of wind tunnel experimental techniques.

Evaluation of modal contribution to the wind-induced responses of tall buildings

Asian Journal of Civil Engineering, 2019

The frequency domain analysis of structures requires the computation of the frequency response functions (FRF) matrix. Obtaining the FRF matrix is a time-consuming procedure, especially for the structures having large number of degrees of freedom (DOF). For the lightly damped structures, the FRF matrix can be estimated by the superposition of the structure's dominant modes. In the present study, the modal dominancy analysis is carried out on the wind-induced responses of tall buildings using the frequency domain modal decomposition method. Two examples of tall structures, including a tall building and a tall TV tower are presented. It is found that the wind-induced dynamic displacement response is dominated by the first vibration mode and the effect of the higher modes can be neglected. For the acceleration response, contribution of the higher modes is observed. However, due to low-frequency content of the wind force spectrum, the first mode has the highest effect on the acceleration response. It is also demonstrated that the modal superposition method with contribution of the dominant modes can significantly reduce the order of the FRF matrix and the computing time.

A Simplified Approach on Dynamic Response of Tall Buildings due to Wind loads - Thida Htun

Wind is caused by differences in pressure. When a difference in pressure exists, the air is accelerated from higher to lower pressure areas. In the field of structural engineering, it includes strong winds, which may cause discomfort and extreme winds such as tornado, hurricane. It plays an important role in design of tall structures because it exerts static and dynamic loads with effects on slender structures. Most international codes and standards make use of the Gust Loading Factor (GLF) by to determine the equivalent static along-wind loading on a structure. Although the traditional GLF method ensures an accurate estimation of the displacement response, it may fall short in providing a reliable estimate of dynamic response components. A single 'factor' can be assessed to account for dynamic effects resulting from gust fluctuations in buffeting wind load condition. Several analytical models have been developed in the past to calculate this dynamic factor which is multiplied by the static response to give the maximum dynamic response of the structure. This dynamic factor is usually referred to as the "Gust Response Factor". Typical high-rise buildings oscillate in the Along-wind, Across-wind, and Torsional directions The Along-wind motion primarily results from pressure fluctuations on the windward and leeward faces, which generally follows the fluctuations in the approach flow, especially in the low frequency range. Therefore, Along-wind aerodynamic loads may be quantified analytically utilizing quasi-steady and strip theories, with dynamic effects customarily represented by a random vibration based "Gust Factor Approach" [1].

Full-scale measurements of wind-induced responses on the Hamamatsu ACT Tower

Journal of Wind Engineering and Industrial Aerodynamics, 1998

In Japan, most high-rise buildings are equipped with vibration control devices in order to improve their habitability by reducing wind-induced vibration. The Hamamatsu ACT Tower is also equipped with active type vibration control devices. For the purpose of confirming the vibration control effects of these devices, observations of winds and vibrations have been carried out. This paper reports on the vibration control effects of the devices on wind-induced vibration, as well as the results obtained from observations of vibration responses of the building during strong seasonal winds and a typhoon.

Vibration of buildings under random wind loads

1980

A method for analyzing the three dimensional dynamic response of wind-excited buildings is presented. The wind and building modes used in the analysis are similar to those used for analyzing along-wind response. The coupled along-wind, across-wind and torsional vibrations are computered using random vibration techniques. The expected maximum translational responses and the and the torsional response are obtained. The objectives

Evaluation of wind effects on a supertall building based on full-scale measurements

Earthquake Engineering & Structural Dynamics, 2000

This paper describes the results obtained from the full-scale measurements of wind e ects on a 70-storey building in Hong Kong. The building which has a height of approximately 370 m is the second tallest structure in Hong Kong. The ÿeld data such as wind speed, wind direction and wind-induced acceleration responses have been measured since 1995 including the close passage of two typhoons; typhoon Sally and typhoon Kent. Detailed analysis of the ÿeld data is conducted. The full-scale measurements are compared with the wind tunnel results obtained in the Boundary Layer Wind Tunnel Laboratory at Western Ontario University. The amplitude-dependent characteristics of damping and natural frequency that were obtained by using the random decrement technique are investigated.

Wind-Induced Vibrations to Tall Buildings and Wind Turbines

2018

While wind generated noise maybe limited in magnitude and effect, wind-induced structures’ vibrations could be a devastation (i.e., Tacoma Bridge Collapse 1940). This occurs with just above moderate wind speed increase, if it can excite a structure with its natural frequencies. When this occur, structures enter a phase of oscillations until collapse. However, with proper understanding of vibrations in structures these vibrations can be eliminated. Studying vibrations can be experimental through wind-tunnel and or by simulations. Wind in buildings can induce two types of motions: static or sustained; as building drift and oscillatory or resonant vibration. Motion is composed of three contributions: sway in two horizontal or perpendicular directions and torsion. This vibration would considerably affect the habitability and stability of building spaces gauged through a life cycle assessment study, habitability perception and determination or acceleration measurements and estimation. Th...

Field Measurements of Typhoon Effects on the Tallest Building in Hong Kang

2009

This paper presents the field measurement results of wind effects on a super-tall building in Hong Kong during the passage of several typhoons in 2007 and 2008. The field data such as wind speed, wind direction, wind pressure, acceleration and displacement responses were simultaneously and continuously recorded from the tall building by a monitoring system installed by the authors. Detailed analysis of the field data was carried out to investigate the wind effects on the super-tall building. The characteristics of the typhoon-generated wind including turbulence intensity, gust factor, integral length scale and power spectral density of fluctuating wind speed were analyzed. The building’s dynamic properties were also identified based on the measurements. The damping ratios of the building were evaluated by random decrement technique, which demonstrated obvious amplitude-dependent characteristics and increased with increasing amplitude of the building during typhoons. The results pres...

A Comparative Study for Dynamic Responses of Tall Buildings Due to Wind Load Distribution Patterns

2017

In this study, the loading pattern of skewed and orthogonal wind condition is analysed to find how much increased or reduced response. As the height of the buildings increases, its vulnerability to wind effects also increases. Codes and Standards utilize the “gust loading factor” (GLF) approach for estimating dynamic effect on high-rise structures for 0, 45 and 90 degree. At the real situation of wind load, these conditions are not covered for strong wind responses. In order to get the responses of other skewed wind direction, various type of loading patterns is assumed to apply the wind load. For the dynamic response analysis of a structure under strong winds, the spectral response method in a frequency domain or the step-by-step integration of motion equation in a time domain is used. This paper aims to make a comparison of various loading patterns of skewed and orthogonal wind in along-wind and across-wind response with respect to the gust response factor (GRF) of dynamic wind lo...

The effect of amplitude-dependent damping on wind-induced vibrations of a super tall building

Journal of Wind Engineering and Industrial Aerodynamics, 2003

Full-scale measurements of wind effects on a 70 storey tall building have been conducted. The tall building that has a height of 367 m is the second tallest structure in Hong Kong. The amplitude-dependent characteristics of damping have been obtained by using the random decrement technique from the field measurements of acceleration responses. The objective of this study is to present detailed investigations into the effects of amplitude-dependent damping on the wind-induced responses of the super tall building based on the measured non-linear damping and wind action characteristics. An efficient and less time consuming digital simulation technique is developed to generate time series of turbulent wind loads acting on the tall building based on the measured wind speed records. The predicted dynamic responses of the building using the actual amplitude-dependent damping characteristics are compared with those computed by using constant damping parameters assumed by the structural designers or estimated from the field measurements in order to evaluate the adequacy of current design practices and to apply that knowledge to structural design of tall buildings. It is observed from this study that the effect of amplitude-dependent damping on the dynamic responses of such a super tall building is significant and knowledge of actual damping characteristics is very important in the accurate prediction of wind-induced vibrations of a tall building.